The use of an cryosurgical apparatus to freeze healthy or diseased tissue in order to necrotize the same is gaining widespread acceptance in the medical profession, particularly among dermatologists. As a result, a number of cryosurgical instrument have been developed and offered in the marketplace in the last few years.
Careful analysis of the problems encountered with the existing prior art devices led to the conclusion that the ideal cryosurgical instrument should provide optimum use of the liquefied gas coolant, produce a predominately spray rather than liquid discharge, have an extremely delicate and precise control of the amount of coolant delivered, and be easily capable of one handed operation by the operator. Unfortunately, as will be seen below, none of the devices on the market possess all of these desired attributes.
A cryosurgical apparatus in common use today by the medical profession is shown in U.S. Pat. No. 3,823,718 issued to the instant inventor. While this apparatus has an insulated container to conserve the liquefied gas coolant and tubing of a sufficient length to produce a predominately spray discharge, it requires two hands to operate and does not have precise control of the amount of coolant delivered.
Another apparatus that is being sold in the market today is shown in U.S. Pat. No. 3,889,681 issued to Waller et al. Since the liquid coolant is contained in a vacuum bottle, considerable waste of the liquid coolant is avoided. Precise control of the amount of coolant is also provided. However, two hands are required for operation (see column 3, lines 36-42). Additionally, attaching a needle directly to the outlet nozzle does not allow the pressurized liquefied gas coolant to vaporize to a sufficient degree with the result that an excess amount of liquid drips off of the needle, thereby causing unnecessary danger during the cryosurgery.
Other instruments used at the present time include those shown in the Brynes patents, U.S. Pat. No. 3,534,739 and 3,651,813, and the patent issued to Reynolds, U.S. Pat. No. 3,739,956. The drawbacks of these devices have been adequately described in U.S. Pat. No. 3,889,681.
The present invention eliminates all the problems inherent in the above described devices. The present invention conserves the liquefied gas coolant by utilizing an insulated container, produces a predominately spray discharge by providing heat exchange means intermediate the application means and the tubing means, affords precise control of the amount of coolant delivered by means of an aperture on the manual squeeze bulb, and is easily capable of one handed operation by the operator because of the adjacent relationship of the handle means and the source of pressurized air.